Mechanisms of failure of the femoral and tibial components in total knee arthroplasty

From 1974 to 1986, 1430 cemented primary total knee arthroplasties were available for analysis. These included 224 total condylar prostheses with a polyethylene tibial component, 289 posterior stabilized prostheses with a polyethylene tibial component, and 917 posterior stabilized prostheses with a metal-backed tibial component. There were 12 failures in the total condylar series including three infections (one early and two late), five loose tibial components, two loose femoral and tibial components, and two unstable arthroplasties. The posterior stabilized prosthesis with the polyethylene tibia demonstrated six failures including two loose tibial components, two loose femoral components, and one supracondylar femur fracture. The posterior stabilized prosthesis with the metal-backed tibial component was associated with seven failures including six infections (three early and three late) and one femoral loosening. No metal-backed tibial components have been revised for loosening. The overall failure rate in this series was 1.7% for all prostheses. The incidence of tibial loosening was 0.53% with an average time to failure of 4.7 years. The incidence of femoral loosening was 0.35% with an average time to failure of 2.0 years. Tibial loosening was related to error in technique: postoperative varus tibiofemoral alignment, varus tibial component position, and excessive tibial resection. The overall infection rate was 0.63% for all total knee arthroplasties, and all were secondary to gram-positive organisms. Presently, the posterior stabilized prosthesis with a metal-backed tibia is the authors' implant of choice. Technical error and infection are the major causes of failure.     

Total knee arthroplasty using cruciate-retaining kinematic condylar prosthesis.

The purpose of the current study was to evaluate the long-term results of the Kinematic I condylar prosthesis with retention of the posterior cruciate ligament. One hundred sixty-eight total knee arthroplasties in 118 patients (mean age, 65.2 years; range, 21-88 years) were inserted with cement, an all-polyethylene patella, metal-backed tibia, and posterior cruciate ligament retention. Sixty-one patients (86 knees) died, one patient had an above-knee amputation, and three patients (five knees) were lost to followup; therefore, 66 knees (excluding revisions) in 50 patients were available for followup at a mean of 15.7 +/- 1.1 years (range, 14-20 years). Of the entire cohort of 168 knees, 13 have been revised: one for medial femoral condyle fracture, one for tibiofemoral instability, one for femoral and two for tibial component aseptic loosening, four for tibial polyethylene wear, and four for patellar component aseptic loosening. The 15-year survivorship free of any component revision excluding infections was 88.7% (confidence interval, 82%-95%). The 15-year survivorship free of radiographic loosening and/or revision of any component was 85.1% (confidence interval, 78%-92%). The current study shows good function and survivorship of the posterior cruciate-sparing Kinematic I condylar prosthesis at a mean of 15.7 +/- 1.1 years.     

Comparison of metal-backed and all-polyethylene tibial components in cruciate condylar total knee arthroplasty

An evaluation of 78 knees in 63 patients using the cruciate-sparing total condylar prosthesis was performed. At a mean of 10 years following the arthroplasty there were 86% good or excellent results in knees with an all-polyethylene tibial component compared to 95% with a metal-backed tibial component (NS). Survivorship at 10 years using an endpoint of revision was 96% (NS) in both groups; using an endpoint of revision or poor knee score was 85% (NS) in the metal-backed compared to 92% (NS) in the all-polyethylene groups; using an endpoint of revision, poor knee score, or complete radiolucent line was 85% in the metal-backed compared to 90% (NS) in the all-polyethylene groups. There were no significant differences in the frequency of radiolucent lines at the last evaluation. Two percent of the tibial components in the metal-backed group had complete radiolucent lines compared to none in the allpolyethylene group. The cruciate-sparing total condylar prosthesis provides satisfactory results with no significant differences between the metal-backed or all-polyethylene tibial components at 10 years.     

Total Knee Arthroplasty With 4.4 mm of Tibial Polyethylene : An Update

Three hundred eighty-seven one-piece, 8-mm tibial components were implanted in 313 patients. All tibial prostheses were manufactured with 4.4 mm of polyethylene. From this group, 116 patients underwent simultaneous bilateral total knee arthroplasty with an 8-mm tibial component on one side and a tibial component with at least 6.4 mm of polyethylene on the other side. Follow-up averaged 11.8 years. The average Knee Society knee score was 81, and the average pain score was 46. No polyethylene wear or osteolysis was identified radiographically. There were 7 knees with tibial radiolucencies, 5 knees with polyethylene failure of metal-backed patellae, and 1 tibial component failure. Survival rates for loosening or revision of any component for any reason were 98.9%, 97.5%, 95.1%, and 93.2% at 5-, 10-, 15-, and 18-years, respectively.     

Should we reconsider all-polyethylene tibial implants in total knee replacement?

The role of modular tibial implants in total knee replacement is not fully defined. We performed a prospective randomised controlled clinical trial using radiostereophotogrammetric analysis to compare the performance of an all-polyethylene tibia with a metal-backed cruciate-retaining condylar design, PFC-Sigma total knee replacement for up to 24 months. There were 51 patients who were randomised into two treatment groups. There were 10 subsequent withdrawals, leaving 21 all-polyethylene and 20 metal-backed tibial implants. No patient was lost to follow-up. There were no significant demographic differences between the groups. At two years one metal-backed implant showed migration > 1 mm, but no polyethylene implant reached this level. There was a significant increase in the SF-12 and Oxford knee scores after operation in both groups. In an uncomplicated primary total knee replacement the all-polyethylene PFC-Sigma tibial prosthesis showed no statistical difference in migration from that of the metal-backed counterpart. There was no difference in the clinical results as assessed by the SF-12, the Oxford knee score, alignment or range of movement at 24 months, although these assessment measures were not statistically powered in this study.     

Dissociation of the tibial component in total knee replacements

Dissociation of the polyethylene component from its metal backing in total knee arthroplasty is a recognized problem regarding the patella. Two cases of dissociation of the metal-backed tibial component from its polyethylene articulating surface presented symptoms of prosthesis failure: persistent pain, swelling, sensations of instability, and gait difficulty. Investigations ruled out prosthesis malalignment, loosening, and sepsis. Precise diagnosis of dissociation of the tibial component was made by diagnostic arthroscopy.     

Problems with cementless total knee arthroplasty at 11 years followup.

One hundred two patients with 131 consecutive cementless total knee arthroplasties that retained the posterior cruciate ligament were followed up prospectively. The average age of the patients was 58 years (range, 32-75 years). The mean followup on the surviving knee arthroplasties was 11 years (range, 7-16 years). The patellar component was metal-backed in the first 112 (85%) knees, cementless all-polyethylene in the last 17 (13%) knees, and two knees had a prior patellectomy. Forty-four metal-backed patellar components (48%) were revised; nine were loose, and 35 had polyethylene wear through. Thirteen femoral components (12%) were revised because of femoral abrasion from a failed metal-backed patellar component. No other femoral component was revised, loose, or had osteolysis develop. Nine (8%) tibial components had failure of ingrowth; eight have been revised. Partial radiolucencies occurred in 53% of the tibias. Thirteen (12%) small osteolytic lesions developed, all around screws or screw holes in the tibial components. At an average of 11 years followup, cementless fixation yielded mixed results: cementless femoral fixation was excellent and metal-backed patellar components had a 48% patellar revision rate. Cementless tibial components had an 8% aseptic loosening rate and a 12% incidence of small osteolytic lesions. Based on these results, the authors have abandoned cementless fixation in total knee arthroplasty.     

The AGC total knee prosthesis at average 11 years

A retrospective study of a series of 126 consecutive primary cemented total knee replacements using the AGC prosthesis is reported. Sixty-two knees were available for long-term review with an average clinical follow-up of 11.4 years (range, 8.4-13.6 years). The survivorship was 95%, defining the endpoint as revision of all components for any reason except sepsis. The average knee flexion was 110.9 degrees. The average Knee Society score was 91, and the average Knee Society Functional score was 67. There was no finding of tibial polyethylene failure, wear debris-generated osteolysis, or tibial or femoral loosening. Seven metal-backed patellae developed wear-through at an average of 80.4 months (7 of 126 for a 5.5% failure rate), with 3 (2.3%) resulting in complete revision. The authors continue to use the AGC prosthesis with an all-polyethylene patella. Compared with historical controls, the AGC has comparable survivorship.     

Screw migration from total knee prostheses requiring subsequent surgery

Complications in total knee arthroplasty directly related to hardware failure other than polyethylene wear are rare. We report 2 cases of symptomatic screw migration into the joint space from total knee prostheses. In the first case, a screw disengaged from a constrained condylar knee prosthesis. Arthroscopy using standard arthroscopy portals and a small arthrotomy were performed to remove the screw. In the second case, symptomatic screw disengagement and posterior migration from the tibial component of a posterior-stabilized prosthesis occurred. Revision with replacement of the polyethylene insert and locking screw was required.     

Clinical comparison of all-polyethylene and metal-backed tibial components in total knee arthroplasty

Based primarily on in vitro biomechanical studies, most total knee arthroplasty (TKA) manufacturers have abandoned the all-polyethylene tibial component (APT) in favor of the metal-backed tibial component (MBT). There is little clinical evidence to support this decision. A retrospective review of cemented TKA using the total condylar prosthesis was performed. One hundred eighteen patients with 131 TKAs were evaluated. Sixty-two of these knee prostheses had tibial components made entirely of polyethylene while 69 had the MBT. There were 13 cases of bilateral TKA in which the APT was used for one knee and the MBT for the other. All patients were examined by the authors for an average follow-up period of six years. Hospital for Special Surgery knee scores and a comprehensive roentgenographic evaluation were obtained. No significant difference was noted between the patients with APT and those with MBT, raising serious doubt on the need for the MBT in patients being treated with primary, cemented TKA.     

Posterior cruciate-retaining modular total knee arthroplasty: a 9- to 12-year follow-up investigation

Between November 1988 and January 1991, 101 press-fit condylar (PFC; Johnson & Johnson, Raynham, MA) posterior cruciate-retaining total knee arthroplasties were performed in 75 patients. All tibial components were modular metal-backed, and all patellar components were all-polyethylene. All living patients were evaluated at an average 10.5 years (range, 9.5-11.8 years). Only 1 knee required revision (at 11.1 years after the procedure), and only 1 other knee had evidence of radiographic failure. The average range of motion was 1 degrees (range, 0 degrees -10 degrees ) to 110 degrees (range, 86 degrees -130 degrees ). At 10 years of follow-up, the probability of prosthesis survival was 100%, and at 12 years, the probability of prosthesis survival was 93.3% (endpoint defined as revision for any reason).     

Long-term results after total condylar knee arthroplasty. Significance of radiolucent lines

In a prospective study of 123 total condylar knee arthroplasties, radiolucent lines were noted at the bone-cement interface about the tibial component in 65% of the knees. In 36%, the line was thin (less than 2 mm) and under either the medial or lateral tibial plateau. In 22%, thin lines were seen under both the medial and lateral plateaus. There was no statistically significant correlation between the occurrence of thin radiolucent lines in any location and the eventual postoperative clinical result. In 7%, thick lines (greater than 2 mm) were noted about the central peg of the prosthesis as well as under both plateaus and were associated with poor results. A 1-mm radiolucent interface was attached to various tibial components, which were then cemented into cadaver knees. For the polyethylene total condylar component, flexion or rotation of the prosthesis more than 5 degrees, angulation of the roentgen beam more than 6 degrees, or offsetting the beam more than 2.5 cm prevented visualization of the radiolucent line. With metal-backed components, more than 4 degrees of flexion obscured the lines. Therefore, extremely careful positioning of postoperative radiographs is essential for evaluating radiolucent lines after total knee arthroplasty.     

Cementless TKA: The preferred method for young,active, and heavy patients

Cementless fixation has the advantage of obtaining biological fixation, which should respond better than cement to the increased stresses that are expected in younger, active, and/or obese patients. In total, 1011 Natural-Knee® cementless total knee replacements were performed by the author from 1986 to 2015 in this patient population. The 10-year failure rates of 20–30% were noted in the early cases, which included the use of metal-backed patellae and use of tibial screws that allowed back-side polyethylene wear debris-induced osteolysis. Reliable bone attachment occurred. The last 760 total knee replacements in this series have been performed with cementless femoral and tibial components, no tibial screws, cemented patellae, and highly cross-linked polyethylene tibia with only one revision for aseptic loosening or osteolysis.     

The Medium-Term Survival Analysis of an All-Polyethylene Tibia in a Single-Series Cohort of Over 1000 Knees

BackgroundTotal knee arthroplasty is a successful elective orthopedic procedure with an increasing number being undertaken. Original knee arthroplasties used an all-polyethylene tibia; however, with concerns over tibial loosening, the trend moved toward the metal-backed variety. Modern designs providing more conformity and changes in manufacturing of the polyethylene make it an equivalent but cheaper option.MethodsWe analyzed the medium-term outcome in 1092 patients with an all-polyethylene tibial component in their total knee arthroplasty.ResultsTwenty-six patients had further surgery on their knee for a variety of reasons. Assessing reoperation for any reason, the 7-year survival rate was 96.96% with an overall infection rate of 0.37%. Seven-year survival analysis using aseptic loosening as a criteria was 99.28%. Both the Short Form 12 physical score and Western Ontario and McMaster Universities Osteoarthritis Index score significantly improved and was sustained at 7 years. Body mass did not correlate to either outcomes or complications.ConclusionAn all-polyethylene tibia in a total knee arthroplasty has good outcome data and high patient satisfaction with good survivorship in the medium term, coupled with potential cost-saving benefits.     

Total knee arthroplasty using a total condylar prosthesis

The authors studied the cases of 52 patients (56 knees) treated with a total knee prosthesis of the type "total condylar" and "total condylar with posterior stabilization" over a 3-year period. Gonarthrosis (41 cases) and rheumatoid arthritis (12 cases) were the major indications. The analysis of functional results proves the success concerning mobility, pain and ability to negotiate stairs after knee arthroplasty. The postoperative radiological results of 44 knees were reviewed and compared to the literature. Proof of the importance of the postoperative axis and the inclination of the tibial component is provided. Few complications were observed. Review of the literature confirms the good results of this type of total knee prosthesis.     

Clinical and radiologic survivorship of cementless tibial components fixed with finned polyethylene pegs

One hundred twenty patients (22 men, 98 women; 144 knees) with uncemented Freeman-Samuelson total knee arthroplasty were followed prospectively. Eighty-one patients had rheumatoid arthritis and 39 patients had osteoarthrosis. The mean follow-up period was 6.8 years. Three different types of tibial components were used: a high-density polyethylene component without stem, a metal-backed tibial component without stem, and a metal-backed tibial component with stem. Progressive varus tilting turned out to be an early sign of failure and occurred in 22% of the tibial components. Revision of the tibial component was done in 17 knees. Survival analysis with revision as endpoint revealed a survival rate of 79% at a follow-up period of 10 years. Cementless fixation of this design using macrointerlocking pegs and no other stabilization resulted in poor fixation and a high revision rate and cannot be recommended.     

Long-term followup of nonmodular total knee replacements

The purpose of the current study was to evaluate and determine the mechanism and etiology of failure of components that failed in long-term followup of Anatomic Graduated Component total knee replacements. The authors previously reported the survivorship of 4583 Anatomic Graduated Component total knee arthroplasties done during a 17-year period. The current study was done to evaluate the etiology and cause of failure of the components that failed. There were six (0.18%) failures of the femoral component. There were 21 tibia components that failed (0.46%). Twelve tibial components failed because of an osteonecrotic lesion in the medial tibia plateau. The clinical survival rate with revision or loosening of one or more components was 98.9% at 15 years. No component was revised for polyethylene wear or osteolysis. This total knee replacement has proved to have minimal wear and excellent longevity with time with no revisions between 10 and 15 years despite having nearly flat-on-flat geometry and retaining the posterior cruciate ligament. The most common cause for revision (12 tibial components) was because of an osteonecrotic lesion in the medial tibia plateau, which developed after surgery and led to loosening.     

Load-bearing capacity of the tibial component of the total condylar knee prosthesis. An in vitro study

The load-bearing capability of the tibial component of total knee prostheses is affected by the coverage of the osteotomized tibial surface by the tibial component. An anthropometric study of the proximal tibia indicated that standard total condylar tibial knee components may significantly underutilize the available weight-bearing tibial surface. The unloaded area values ranged from 6% to 43% in males and from 1% to 25% in females. An experimental study of the load-bearing capability of both standard tibial components and tibial components custom-fitted to conform to the periphery of the upper tibial surface was performed. Improvement in single load to failure with the conforming prosthesis averaged 29% in females with stemless prosthesis, 21% in females with stemmed prostheses, 41% in males with stemless prostheses, and 89% in males with stemmed prostheses. Post-test examination of the failed tibiae with conforming implants indicated failure by major fragmenting of the proximal tibia rather than cancellous bone crushing, suggesting that the maximal load-bearing ability of the upper tibial surface was more nearly being achieved. The results demonstrate the benefit to be gained by fully utilizing the available tibial surface for load transmission across the joint and suggest that use of custom-fitted tibial components has considerable merit.     

Long-term results of low contact stress mobile-bearing total knee replacements

Five hundred ninety-eight consecutive primary low contact stress total knee replacements were done in 502 patients between 1985 and 1990. Clinical review was available for 495 knees (406 patients), 228 knees with meniscal-bearing prostheses and 267 knees with rotating-platform prostheses. The average followup was 12 years (range, 10-15 years). The average postoperative knee and functional scores were 87 points and 75 points, respectively. The average postoperative range of motion was 110 degrees. Fifty-six knees (11%) required revision for excessive wear of the tibial insert (41), dislocation (10), patellar polyethylene breakage (one), component loosening (one patellar, one tibial), and infection (two). During revision, osteolysis (20 knees), patellar polyethylene failure (33), and femoral component fracture (one) were seen. The overall survivorship was 88.1% at 15 years using Kaplan-Meier analysis. The survival rate was 83% for the meniscal-bearing prostheses and 92.1% for the rotating-platform prostheses. The Low Contact Stress mobile-bearing knee prosthesis has no superiority over that of fixed-bearing knees, especially for the meniscal-bearing design in prevention of polyethylene failure or revision. Based on the results of this study, the use of the LCS meniscal-bearing prosthesis does not appear to be justified.     

Total knee arthroplasty in elderly patients. Comparison of tibial component designs.

The authors examined 98 total knee arthroplasties in 73 patients who were 80 years of age or older at the time of surgery (average, 82 years; range, 80-90 years). The follow-up period averaged 4.5 years (range, 2-12 years). The patients were divided into two groups based on their tibial component design. There were 38 all-polyethylene tibial components in 28 patients and 60 metal-backed tibial components in 45 patients. There were 61 (62%) excellent, 30 (31%) good, 2 (2%) fair, and 5 (5%) poor results. Three of the five poor results required revision for septic failure. Of the knees with an all-polyethylene tibial component, 20 (53%) were rated as excellent, 15 (39%) as good, and 3 (8%) as poor. One of these knees rated as poor required revision for septic failure. The knees with a metal-backed tibial tray had 41 (68%) rated as excellent, 15 (25%) as good, 2 (3%) as fair, and 2 (3%) as poor. Both of the knees with poor results required revision for septic failure. Stratifying the results by component composition revealed 97% survival for both types of tibial trays. These results were obtained at 12 years for the all-polyethylene components and at 8 years for the metal-backed prosthesis. In conclusion, the authors believe that total knee arthroplasty is a reliable and durable procedure in the treatment of knee arthritis in the elderly. Elderly patients may represent a special case because they are generally less active than younger patients and may place less stress on their prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)